SAG actor doing a non union project...on accident?

I booked a PSA. My Manager failed to tell me that it's non union. Great MGR, right? Sometimes PSAs fall under no union affiliation jurisdiction. Well, I shoot tomorrow, and flights are already booked. Obviously I'm doing the job. I'm far from being an overworked actor. Believe me I'm NOT in the top 3%. What I want to know is, does anyone out there know what the penalties are? Thanks!